Secure SMS storage

treequell

[deleted] Is the filesystem-based encryption on GrapheneOS not sufficient? If you don't want any other apps accessing your SMS messages, then deny them the SMS permission.

[deleted]

treequell Hi,
The Original poster (OP) wants to protect their SMSes from their family members and 'nosy' friends (The people stated will have physical access to their device).

treequell

[deleted] The Original poster (OP) wants to protect their SMSes from their family members and 'nosy' friends (The people stated will have physical access to their device).

Thanks for pointing that out.

whitherunderground

In that case, I would setup a secondary user with access to phone calls and SMS from that user denied. Then make sure you switch to that secondary user before giving your phone to anybody else. This is an ideal use case for setting up a secondary user.

[deleted]

whitherunderground I think you should use a different profile for personal use and set it up like this:

Disable the Messages app (If not possible via Settings, use Wireless/USB debugging)
Install all the apps you need
Disable Installation of new apps in this profile via Settings in Owner profile, to mitigate the risk of third-party SMS app being installed on this profile.

whitherunderground

Thanks all for the thoughtful replies!

[deleted]

How can Silence encrypt the SMS/MMS database stored locally on your device? Does it store all SMSes and MMSes in its own app-based datavase and then delete them from OS' SMS database or something?

I think so? When Silence is the default SMS app of the Owner profile and receives a text, that text never shows up in the stock app, or in the stock app of any newly-enabled profiles (whereas when the stock app is the Owner's default, any texts received show up in the stock app of every profile with SMS permissions).

[deleted]

I think you should use a different profile for personal use and set it up like this:

Disable the Messages app (If not possible via Settings, use Wireless/USB debugging)

Install all the apps you need

Disable Installation of new apps in this profile via Settings in Owner profile, to mitigate the risk of third-party SMS app being installed on this profile.

So this is what I was hoping to do when I found out about GOS's profiles support. The main problem I ran into is that SMSes can't be disabled in a profile's settings without also disabling the phone (and I'd need the phone in my regular-use profile). I'm not sure I know how to disable SMS via Wireless or USB debugging though -- do you have a link to some instructions on how to do that?

It also makes me a little nervous that all those SMSes just sit in the OS database ready to be read by any profile with SMS permission, but I guess the trick to that is to deny that permission to everything except the SMS profile (which should maybe be the Owner profile since it always has SMS access?).

But yeah I guess if there's a way to deny a profile SMS access without denying phone access, then a separate SMS profile could work. So any tips on how to do that would be very welcome!

[deleted]

Let me just mention that Neo Launcher
https://github.com/NeoApplications/Neo-Launcher
supports password protecting apps from its settings, including Settings itself which some may find very beneficial. So you could protect your SMS and other sensitive apps while the phone is unlocked. I am aware the launcher doesn't have frequent updates, but if anything, it has better functionality than the stock launcher. Just consider it, it worked well for me in the past. Any questions? Just ask.

[deleted]

[deleted] supports password protecting apps from its settings

This can be bypassed with a third-party launcher

[deleted]

[deleted] i would password protect any such app that supports downloading/sideloading APK as well (browser, file manager). As OP said he wants to protect himself from family and nosy friends who usually aren't very knowledgeable (from my own experience). From this POV this is already an overkill.

[deleted]

[deleted] i would password protect any such app that supports downloading/sideloading APK as well (browser, file manager)

Any app's MainActivity (The activity that is used to open the app) can be launched by invoking it via shell or an app like App Manager, thus bypassing 'password protect' stuff

[deleted] As OP said he wants to protect himself from family and nosy friends who usually aren't very knowledgeable (from my own experience)

Well, yeah.

[deleted]

[deleted] I would second @treequell in saying filesystem encryption should be sufficient and if you don't trust your family, friends or acquaintances, tell them so or alternatively ask if you can have a browse through their device, I am sure that would shut up many.

[deleted]

whitherunderground I'm not sure I know how to disable SMS via Wireless or USB debugging though

You cannot disable SMS itself, but you can disable the stock SMS app. That's Why I recommended creating a different profile, installing all apps you need in It except apps that allow to Read SMS, disabling the Stock SMS app with ADB and then disabling new app installation for this different profile. Once having done this, Do not give access of the Owner profile to anyone; Give access to this different profile only.

whitherunderground

[deleted] disabling the Stock SMS app with ADB

Hmm, so I think in theory that might work, but following these instructions and doing it with adb shell pm disable --user 10 com.android.messaging' (or with--user 0`) gets me an error message like the one in this probably-won't-be-fixed-upstream issue.

disable SMS via Wireless

Maybe there's some other way to do this that I'm overlooking?

[deleted]

whitherunderground Maybe there's some other way to do this that I'm overlooking?

No. Thanks for telling me about that github issue btw

[deleted]

Download Simple SMS Messenger (part of Simple Mobile tools). Set it as a default SMS app in Settings-Apps-Default apps. Disable built-in SMS app. Uninstall Simple SMS Messenger. You no longer have a working SMS app on device. Check again in Settings-Apps-Default apps.

whitherunderground

[deleted] Download Simple SMS Messenger (part of Simple Mobile tools). Set it as a default SMS app in Settings-Apps-Default apps. Disable built-in SMS app. Uninstall Simple SMS Messenger. You no longer have a working SMS app on device. Check again in Settings-Apps-Default apps.

Well, I want a working SMS app somewhere on the device -- just not in the profile I regularly use for phone and for non-SMS apps. Your comment made me think that maybe I could use this trick to disable the stock app globally and then leave me with no SMS app in a regular-use profile, but as Skyway mentioned it looks like for some reason it's only possible to disable the stock app in the Owner profile. So I don't think the install-third-party-disable-stock trick does much good unfortunately. Thanks for the idea though.

Your suggestion of a lockable launcher seems to be the only additional alternative here to the options of Silence or never sharing one's phone. I would still worry that with a locked launcher someone would accidentally stumble into a bunch of compromising text messages via another app that opens the SMS app, but you're right that it would at least reduce the risk.

I continue to share @Graphite's bafflement that there aren't more developers in the world who seem to be worried about what seems like an incredibly common use case. I thought I was missing some stupidly obvious solution, but based on the responses here I guess that's not the case... I'd love to hear further suggestions if anybody else has them though!

whitherunderground

I'm bumping this thread because Silence, which I think has been the only available solution for this problem for the past year, will soon stop working due to the 32-bit sunset, and has now been definitively abandoned anyway (and, AFAICT, was never very good for anything except encrypted storage in the first place).

I've searched again for apps that have emerged since I first posted this, and for strategies like GrapheneOS user profiles that could solve the problem in other ways. I haven't found anything but I figured I'd bump this thread in case anybody has found any solutions. (Note that the second link above won't load for me, presumably because git.silence.dev's web certificate has expired, but its title was "Canary warrant expired, project is dead. Please post forks or replacement apps here"; it had no replies as of July 11.)

It still seems to me that this particular threat affects nearly every single mobile phone user and is a serious threat to people dealing with domestic abuse and similar situations, so I'm still slightly amazed that no solution is available. Hopefully some eager dev will see posts like this one and put together a nice accessible tool.

Meantime, has anybody found a way to securely lock and isolate SMS storage?

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